2,049 research outputs found

    The advent of universal public education in Virginia and its Valley: Reconstruction through the Progressive Era, 1865-1920

    Get PDF
    Prior to 1870 there was no such thing as a public school in the state of Virginia, nor in most of the United States. History regards Reconstruction as a lost moment in time which failed to realize its potential to secure the full promises of freedom. The historiography rightly focuses on this ugly legacy of Reconstruction in a racially segregated south. Virginia’s Redeemer Democrats had rested political control from Radical Republicans by the ratification of the state’s 1870 Constitution. Virginia’s 1902 Constitution is rightly remembered for effectively disenfranchising blacks and poor whites. Yet, the promise of education was introduced to Virginia overnight thanks to the same 1870 Constitution and expanded by the 1902 Constitution. This study examines the evolution of education and progressive education in the form of curriculum, modernization, professionalization, and organizational reform in several periods. The first, 1870 to 1886, will be examined as the period in which Virginia was solely focused on entrenching the idea of universal public education in the minds of its citizenry. Simultaneously it worked to co-opt the already existing rudimentary common school system which existed prior to the Civil War. The second, 1886-1900, is examined as the period when the first fifteen years of experience produced a large degree of organization and standardization across the state; which was ahead of the national movement of the 1900s. This organization and standardization would not be led by national figures but by the new cadre of professional educators at the local level who capitalized on the initiative, work, and experience they had gained in the first period. The period of 1900-1912 will be viewed as the time when Virginia leapt onto the national stage as an educational leader in its own right. It installed an array of progressive educational initiatives and ideals. Finally, the period from 1912-1920 will serve as an epilogue to portray an entrenched System of Public Free Schools which remains largely unchanged today. This system, though segregated, served both black and poor white alike and radically transformed life in Virginia

    Plasma Diffusion in Self-Consistent Fluctuations

    Get PDF
    The problem of particle diffusion in position space, as a consequence ofeleclromagnetic fluctuations is addressed. Numerical results obtained with a self-consistent hybrid code are presented, and a method to calculate diffusion coefficient in the direction perpendicular to the mean magnetic field is proposed. The diffusion is estimated for two different types of fluctuations. The first type (resuiting from an agyrotropic in itiai setting)is stationary, wide band white noise, and associated to Gaussian probability distribution function for the magnetic fluctuations. The second type (result ing from a Kelvin-Helmholtz instability) is non-stationary, with a power-law spectrum, and a non-Gaussian probabi lity distribution function. The results of the study allow revisiting the question of loading particles of solar wind origin in the Earth magnetosphere

    Scaling of the electron dissipation range of solar wind turbulence

    Full text link
    Electron scale solar wind turbulence has attracted great interest in recent years. Clear evidences have been given from the Cluster data that turbulence is not fully dissipated near the proton scale but continues cascading down to the electron scales. However, the scaling of the energy spectra as well as the nature of the plasma modes involved at those small scales are still not fully determined. Here we survey 10 years of the Cluster search-coil magnetometer (SCM) waveforms measured in the solar wind and perform a statistical study of the magnetic energy spectra in the frequency range [1,1801, 180]Hz. We show that a large fraction of the spectra exhibit clear breakpoints near the electon gyroscale ρe\rho_e, followed by steeper power-law like spectra. We show that the scaling below the electron breakpoint cannot be determined unambiguously due to instrumental limitations that will be discussed in detail. We compare our results to recent ones reported in other studies and discuss their implication on the physical mechanisms and the theoretical modeling of energy dissipation in the SW.Comment: 10 pages, submitte

    A Hot Helium Plasma in the Galactic Center Region

    Full text link
    Recent X-ray observations by the space mission Chandra confirmed the astonishing evidence for a diffuse, hot, thermal plasma at a temperature of 9. 10710^7 K (8 keV) found by previous surveys to extend over a few hundred parsecs in the Galactic Centre region. This plasma coexists with the usual components of the interstellar medium such as cold molecular clouds and a soft (~0.8 keV) component produced by supernova remnants, and its origin remains uncertain. First, simple calculations using a mean sound speed for a hydrogen-dominated plasma have suggested that it should not be gravitationally bound, and thus requires a huge energy source to heat it in less than the escape time. Second, an astrophysical mechanism must be found to generate such a high temperature. No known source has been identified to fulfill both requirements. Here we address the energetics problem and show that the hot component could actually be a gravitationally confined helium plasma. We illustrate the new prospects this opens by discussing the origin of this gas, and by suggesting possible heating mechanisms.Comment: 9 pages, accepted for publication in APJ

    A comparison of wave mode identification techniques

    Get PDF
    The four point measurements available from the Cluster mission enable spatiotemporal effects in data sets to be resolved. One application of these multipoint measurements is the determination of the wave vectors and hence the identification of wave modes that exist within the plasma. Prior to multi-satellite missions, wave identification techniques were based upon the interpretation of observational data using theoretically defined relations. However, such techniques are limited by the quality of the data and the type of plasma model employed. With multipoint measurements, wave modes can be identified and their wave directions determined purely from the available observations. This paper takes two such methods, a phase differencing technique and k-filtering and compares their results. It is shown that both methods can resolve the k vector for the dominant mirror mode present in the data. The phase differencing method shows that the nature of the wave environment is constantly changing and as such both methods result in an average picture of the wave environment in the period analysed. The k-filtering method is able to identify other modes that are present

    “Savages Who Speak French”: Folklore, Primitivism and Morals in Robert Hertz

    Get PDF
    Hertz's analysis of the Alpine cult of Saint Besse apparently marks a break from his studies of death, sin and the left to folkloric studies. This analysis helps one to understand the personality of Robert Hertz. His sociological curiosity about folklore reveals his ambiguous position in social sciences at the beginning of the twentieth century. His text appears to be a variation from the Durkheimian norm, but another reading could suggest that Hertz continued and went beyond Durkheimian thought to something between sociology of the modern world and engaged socialism. Through this study, Hertz linked his political ideals, his work in ethnology and his desire for social involvement. The cult of Saint Besse perpetuated as much religious tradition as local identity. The Alpine people were presented in the text as wilful perpetuators of an ideal social order, whose loss for his contemporary city dwellers Hertz feared. The alpine Other, marked by a material and moral backwardness, represented for activist and socialist Hertz one of the paths of balanced social organization that stabilized the identity of a group across time if it fit rather well into the folkloric stereotypes of the beginning of the twentieth century. Finally, by linking events in Herz's life (e.g., the accidental Alpine death of his father), this article suggests that the legend of Saint Besse embodied several recurring motifs in Hertz' career: the accidental deaths of saint and father by falls, the military role of the saint and of Hertz himself

    On the multispacecraft determination of periodic surface wave phase speeds and wavelengths

    Get PDF
    Observations of surface waves on the magnetopause indicate a wide range of phase velocities and wavelengths. Their multispacecraft analysis allows a more precise determination of wave characteristics than ever before and reveal shortcomings of approximations to the phase speed that take a predetermined fraction of the magnetosheath speed or the average flow velocity in the boundary layer. We show that time lags between two or more spacecraft can give a qualitative upper estimate, and we confirm the unreliability of flow approximations often used by analyzing a few cases. Using two‐point distant magnetic field observations and spectral analysis of the tailward magnetic field component, we propose an alternative method to estimate the wavelength and phase speed at a single spacecraft from a statistical fit to the data at the other site

    The Ring Imaging Cherenkov detector (RICH) of the AMS experiment

    Full text link
    The Alpha Magnetic Spectrometer (AMS) experiment to be installed on the International Space Station (ISS) will be equipped with a proximity focusing Ring Imaging Cherenkov (RICH) detector for measuring the electric charge and velocity of the charged cosmic particles. A RICH prototype consisting of 96 photomultiplier units, including a piece of the conical reflector, was built and its performance evaluated with ion beam data. Preliminary results of the in-beam tests performed with ion fragments resulting from collisions of a 158 GeV/c/nuc primary beam of Indium ions (CERN SPS) on a Pb target are reported. The collected data included tests to the final front-end electronics and to different aerogel radiators. Cherenkov rings for a large range of charged nuclei and with reflected photons were observed. The data analysis confirms the design goals. Charge separation up to Fe and velocity resolution of the order of 0.1% for singly charged particles are obtained.Comment: 29th International Conference on Cosmic Rays (Pune, India
    • 

    corecore